Class D Technology

Just to ad to Ralph, why would Technics (SE-R1) strive to develop twice the current going switching frequency, if there was no point to it.
But you pay for this first off development $30k! But the price will come tumbling down when others adopt it. But it also still needs to be higher again.

Cheers George

Whatever Ralph meant the mid-fi comment did make me laugh knowing that the sound I hear from practical Class D amps today (like the ones I own which are neither the least or most expensive) is not mid-fi by any reasonable listening standard.

I suppose mid-fi is in the eye of the observer or the ear of the listener.

Nevertheless respected tube amp makers like Arc and Rogue have been on teh bandwagon for a number of years now knowing Class D is the ticket to get the sound their customers might like with most of the speakers out there today that are not overly  tube amp friendly. My local dealer sells Arc and Rogue (mostly tube amps for many years) and has jumped on teh Class D bandwagon even saying that the Rogue models he sells are the best sounding with the speakers popular with his customers (Magnepan and Sonus Faber).

@mapman I totally agree with the above statement. I'll also point out that Magnepan themselves say on their website to avoid Class D. 

That's why i purchased TOTL Emotiva seperates. I was confident that the dealer where I purchased the Maggies carried and recommended Emotiva as well. It sounded good when I purchased the Maggies.

Fast forward 6 months and I can truly say the Emotiva gear was mid fi. The Rogue gear outclasses in in every way. I don't care that Magnepan says to avoid Class D. They are wrong for making such a blanket statement, and I was wrong for heeding the advice.

I am finally very happy.

Arc and Rogue have been on teh bandwagon for a number of years now knowing Class D is the ticket to get the sound their customers might like

It's called maximizing profits, as Class-D is many x cheaper to produce.

Cheers George 

Fast forward 6 months and I can truly say the Emotiva gear was mid fi. The Rogue gear outclasses in in every way. I don't care that Magnepan says to avoid Class D. They are wrong for making such a blanket statement, and I was wrong for heeding the advice.

I am finally very happy.

Magnepan recommends high current Class AB because they know their panels work well with that. Class D doesn't have a consistent track record and they don't want that to cost them in sales and returns. They also don't want to bad mouth Class D because their dealers sell it. I believe that their most recent advice is listen to their panels at the dealer with the amplification that is going to be used.   

Emotiva gear is mid fi for sure. Their most expensive amp is $1000 and Rogues cheapest amp is $1300. Hardly a fair comparison ;-) 

I keep reading the negative comments on class D amps here and then listen to my Devialet 1000 to Maggie 20.7 setup for flaws.  I know the Devialet is a class D hybrid design..... but the system just blows away all the other amps I have tried.   

I keep reading the negative comments on class D amps here and then listen to my Devialet 1000 to Maggie 20.7 setup for flaws. I know the Devialet is a class D hybrid design..... but the system just blows away all the other amps I have tried.

For 35k I would hope so. I believe that this hybrid is unique in that it doesn't require an output filter....it's kinda like a thread where people are debating if class B amps can compete with tube amps and someone chimes in that their Class AB amp sounds brilliant and they don't get why folks rag on Class B.

@seanheis1 Emotiva and Rogue is more compatible price wise than you stated. If you are looking at top of the line seperates, the monoblocks are $2398 a pair, and the preamp is $999- excluding holiday sales. So you are looking at $3397, a whopping $103 less than a Rogue Pharoah.

Performance wise? The improvement with the Pharaoh is staggering.   

The Rogue Pharaoh is an integrated though? Emotiva Monoblocks running 600 watts of power with their best preamp compared to a 185 watt Rogue integrated?? You can’t compare pricing on monoblocks plus preamp with an integrated that has a fraction of the power. It’s 3 pieces compared to 1.

Those Emotiva monoblocks will also run in Class A mode. If Emotiva were to sell a 185 watt integrated, it would be priced around $500 and of course couldn't compare with a $3500 Pharaoh.

@seanheis1 Of course you can compare the two. And your answer tells me that you are falling into the same trap I did. 

Yes, the Emotiva had more power, switchable Class A, etc. It also doesn't sound all that great.

I was making a point that you can buy that or for $103 more, you can have an awesome amp. We are talking retail to retail new.

I purchased the Emotiva gear during one of their sales. I purchased the Rogue in 9/10 condition preowned here. I actually paid less for the Rogue than I did for the Emotiva gear. And it's not a fair fight at all. The Rogue sounds so much better.

The newer Class D integrateds I have heard like BC C5i and Rogue Pharoah and Sphinx are game changers for me. Prior to these, I would not have thought to ever replace separates with an integrated amp, but I would strongly consider that with any of these. The only downside is my Class D monoblocks are 500w/ch and all those go to good use in my larger system. In my smaller system, especially with more efficient speakers, the 60w/ch C5i comes very close to doing everything ever needed though a few more watts/ch would still likely only benefit.

60w/ch Class D and truly digital C5i has phono and line level inputs in addition to all the usual digital ins. Plus an outstanding headphone amp as well. Just add speakers and a digital source and you may be set with everything most would ever need sound wise.   In a single easily handled and manageable package smaller than the size of a shoe box.

I decided to try this (latest and greatest Class D and digital technology from Bel CAnto) prior to trying a tube integrated amp in this system and guess what its not going anywhere.

You guys are right! Please do not forget the Lyngdorf 2170 which is just amazing and class D. It is a dac, int amp, and room correction all in one. The room correction is SOTA and what makes it one of the best options out there. 

Neal at Sound Science sells them. See his ad here on the Gon. It is replacing, and besting, $30,000 plus of separates. 

Whatever Ralph meant the mid-fi comment did make me laugh knowing that the sound I hear from practical Class D amps today (like the ones I own which are neither the least or most expensive) is not mid-fi by any reasonable listening standard.

@mapman  Do you think that because we've taken this technology very seriously that at the same time we don't?

If I can point out some things without people trying to put words in my mouth, first- tube amps are rarely mid-fi. The term 'Mid-fi' refers to equipment generally sold in box stores like Best Buy (not including their in-store Magnolia dealerships); stamped out to make money. Tube amps are usually too expensive for that (tube power is generally expensive, which is why there were many high efficiency speakers on the market when tubes were the only game in town decades ago).

The thing about most solid state is that the specs really haven't changed a whole lot since the late 70s or early 80s. Like I said, compare a Kenwood amplifier a Krell and you will see what I mean. The big difference is power (on paper). Bandwidth and distortion are almost the same. Of course a Krell is built better, has bigger heatsinks and bigger power supplies. And its not sold in box stores.

Class D has almost entirely taken over at the bottom end of the audio market. And the middle part too. You can't buy a boom box now days that isn't class D. For the number of class D amps in total on the market, only a tiny minority (the ones that generally have our attention) are considered high end. Many of them use the same modules found in mid fi gear.

Think about that for a moment before railing on me? I'm only working with the facts here so don't shoot the messenger. If you look at a high end tube amp or a traditional solid state amp, **NONE** of them use parts/circuitry/assemblies also found in mid fi gear.  This is something different about class D and has entirely to do with how inexpensive the technology actually is.

(To give you an idea of that, I have a module on my desk that was sent to me by a customer (who happens to be the vice president of Phillips Semiconductor). This was one of their best modules built about 12-13 years ago. It makes 100 watts per channel and is a stereo module that is complete except for the power supply. It even has connectors on the board for easy hookup. The specs are quite good (Phillips TDA8920B, scans at 317KHz!; not bad for decade-old technology; faster than some amps made today and features no 'dead time') and it sounds alright too. In quantities of 1 it cost $25.00. I know of at least one 'high end' amp that uses this module that cost $2500.00. This module is the size of a pack of cigarettes complete with connectors and heatsink.)

So when I talk about mid fi and class D, you **should** know why now. I think a lot of posters here are attaching a negative meaning to the 'mid fi' term that does not exist; Just because its mid fi does not mean it has to sound bad and I can point to plenty of examples (we could start with the Radio Shack Lineaum speakers). What I'm seeing in class D is something I've not seen in audio before- amplifiers that use the same parts as a mid fi amp as in a high end amp. In fact its safe to say that class D has lifted mid fi performance to what many would have called 'high end' only a decade earlier.

So you might like your amp and I'm not disputing that! OK, I'll say it again, you might like your amp and I'm not disputing that. But if you think that the amp does not share a lot with mid fi gear you are ***really*** mistaken.

There is one other thing that keeps getting left out of this discussion. Its a simple fact that no matter what the amp is, if you make it work hard for a living its not going to sound as good because its distortion will be higher. This is easy to hear and easy to measure!! You can see it in the specs of any amp. Tube amps in general are best experienced when driving higher impedances 8 ohms or more. All output transformers are more efficient driving higher impedances and also will have wider bandwidth (its not unusual for an output transformer to loose an octave of low frequency bandwidth going from the 4 ohm tap as opposed to the 8 ohm tap). For this simple reason, Magnaplanars and Ohm Walsh loudspeakers are not the best candidates to really tell how good a tube amp actually is (the tube amp will sound better on a load that's easier to drive, and so will any solid state amp). My speakers at home and here at the shop are both 16 ohms and very different designs; both extremely transparent. When both amps are on a level playing field their differences are more easily assessed.

At any rate, if you are happy with what you hear than that's really what's important. If you have audiophile nervosa, which is a deadly disease (I've had it for decades and its no picnic) you are always left wondering what's around the next bend, how you can arrange things to get better sound. I've outlined already how class D has to improve (FWIW, some of the complaints I have apply to regular amps as well), which we hope to address in our design.

Mid fi has a negative connotation in these parts. That’s all. One can either laugh or be insulted. Best to not use the term unless that is the message intended.

Some amps of any type can be labeled as mid fi compared to others of same type, SS Class D, tube, whatever based on whatever criteria one chooses including the sound quality.

The point is not all of any type are created equal. Some of each type these days compete in the big leagues but play the game differently. Some in the minor leagues.

Also safe to say Class D competes well in all leagues at most any price point these days.

Its generalizing and labeling all products of a particular type equally for better or for worse that causes problems just like labeling all persons of a particular nationality or religion negatively causes similar confusion and problems, just of a lesser importance in the case of hifis.

The BelCanto C5i in particular has shocked me in that my quite tube amp friendly Triangle Titus speakers sound the best ever with it. The 60 w/ch are Ok but not the best with any of my OHM or Dynaudio speakers though I have had visitors from Agon still compliment the sound with those even. Which just goes to show it all depends. Class D amps play the game radically different than OTL tube amps do. But both can deliver big league results (Class D for less perhaps especially when cost of speakers factored in) based on my listening experience perhaps both even with easier load speakers that are required more for the OTL or tube amps but easier load in general tends to benefit all amps to some extent when done right.

Also I would note that modern OHM Walsh speakers (especially the larger models) are a good bit more efficient than Magnepans and not as tube amp unfriendly as one might anticipate. I found Magnepan to need power (though not so much current) to a much greater degree than OHM when I owned both.

Why do the people who say they don't like class D mention the class D amps they have heard?  One guy slammed the H2o's that he had obviously never even heard.....how ridiculous is that?!  No not all class D amps are great but there are plenty that are EVERY BIT AS GOOD (and better) than any other design.

I had a Bel Canto Class D amp a few years ago and it was awful. However, I heard the Channel Islands Audio Class D mono block amps a while ago at an audio show and judged them to be outstanding.  Class D amp technology has progressed and I don't doubt it will be the wave of the future for audiophiles.  

I had the Ice Amp 125ASX2 and it was awful. 

Folks - really enjoyed reading this long thread. Very much appreciate the education and the discussion!

Just bought a pair of Bel Canto Ref600m on the Gon and found this thread after doing so.

I opted to go this route while trying to upgrade my amplification - which is currently a Supernait 2 driving PMC Twenty 26s. While the sound can be quite nice at times I’m thinking I’m underpowered - the Snait 2 is only 80 watts and the speakers are not an easy load - sensitivity of 86 reported (though probably lower based on some of my reading) and can go down to under 4 ohms. I’m hoping for a more dynamic range for orchestral music which sounds a little congested/strained currently. Plus I’d just like to hear the Bel Cantos.

I landed here after finding other options (with an eye to Class A) for getting more power to be a challenge - and thus not able to pull the trigger on something. I looked quite seriously at a demo Pass labs 250 INT - but while I am sure they are really great - are HUGE and serious $$$. I’d also have to get a new rack to hold them - even more $$$ and space.

Basically, Class D appealed due to cost and size. Reviews have been solid. The pair was under 4k less than a year old. And if I don’t like them they can go back to the Gon and I will be out a small amount of $$$ to test them in house! Pretty good deal (says the recent purchaser!) The new Bel Cantos is the new chip or whatever - different technology used than all their other units - so I am hoping for good things. this is going to cost me as I skipped the monos from Wyred for Sound cyber monday special - could of had those 1000sx pair for around $2200 - hope I made the right call!

anyhow - Really glad to have found this thread!

I’ll be sure to post how they sound!

Pass labs 250 INT - but while I am sure they are really great - are HUGE and serious $$$.

In Australia the Belcanto Ref600’s are $8k around the same as the Pass 250 int.
The new BC Ref600 monoblocks use the latest NC500 Hypex modules with moded from what I was told output filters (cascaded?) by BC. They sounded very good to me with a certain Raven ribbon tweeter that presented a very flat 8ohm load in the uppermids/highs. Read my post here.
https://forum.audiogon.com/discussions/class-d-technology/post?postid=1372318#1372318

Cheers George

" Mid fi has a negative connotation in these parts. That’s all. One can either laugh or be insulted. Best to not use the term unless that is the message intended."

     Well said, mapman.

Ralph (atmasphere) stated:

" What I'm seeing in class D is something I've not seen in audio before- amplifiers that use the same parts as a mid fi amp as in a high end amp. In fact its safe to say that class D has lifted mid fi performance to what many would have called 'high end' only a decade earlier."

Georgelofi acknowledges the benefits of class D but mentions its low cost in a manner that suggests it's not a further benefit, implying that sound quality and low cost are mutually exclusive and that we should, therefore, look down upon this technology that dares to sound so good and be so affordable at the same time.  

     I'm a fan of all good class D amps and admit it's a bit annoying to hear them described as 'mid-fi'. But it is true that class D amps today are in a wide range of products that do cover a wide spectrum of sound quality: from 'mid-fi' applications such as car audio, boom boxes, home receivers and powered full-range speakers/subs (that enabled better sound for less cost than the previous amps used)  to  'high-end' applications  such as the state of the art line of modules from Hypex ,  Anaview/Abletec and Pascal modules that are used in world-class amps from Jeff Rowland, D-Sonic, Mark Levinson, Marten, Merrill Audio, Audio Research, Halcro and possibly even Atma -Sphere in the near future.
     .
     These are just some thoughts from my perspective from the outside as a consumer looking in.  I have no amp design experience or knowledge and wish all amp companies, regardless of the amplification type employed,  continued success.

Tim    

   
 

Congratulations geekboy!

Be patient with your new BC Ref600S before evaluating them seriously.... Unless they were completely broken in before you got them, it will take anywhere from a few hundred hours to about 1000 hours for them to reach their full potential.... Try leaving them powered up 24/7 and let them crunch a signal at medium lowish volume... E.g. the interstation hash from an FM radio tuner.... That should clear their musical throat quite nicely. Full break-in on class D amps is essential... The difference is quite staggering.

Once they have stabilized, the careful selection of PCs will bring them to even newer hights. For PCs that are not super-expensive, I would suggest Shunyata Alpha

Regards, Guido

ee

Guido have you heard ref1000m amps respond similarly to power cords?  In what way specifically?  Thanks.

noble100
Georgelofi acknowledges the benefits of class D but mentions its low cost in a manner that suggests it’s not a further benefit,

Now that’s twisting words.
I suggested that future technology in higher switching frequency will be of great benefit to class-d, so then the output filter can do it’s job properly without effecting the audio band.

We’re trying to band fix the switching noise problems with some innovative (ML below) (Belcanto my last post) but not completely successful filter ideas.

Just look for one at the $50k Mark Levinson No53 Class-d monos. 4 x massive inductors for the output filter probably cascaded to get rid of the switching noise. Speaker designers know that doing this with filters has it’s own set of interaction problems. Didn’t get a great Stereophile review/measured performace.

http://www.stereophile.com/content/mark-levinson-no53-reference-monoblock-power-amplifier#kXGk3Vi1RAApjFoi.97

Like I said before, I’ll be the first to get a Class-D once the switching frequency is around 3-5mHz so the filter can do it’s job properly, but at the moment nothing save for the very exclusive $30k Technics SE-R1 with a higher (double) but not high enough switching frequency, then my linear amps will become boat anchors.

Cheers George

Hi George,

     I didn't intend to twist your words, sorry.

     I reread your posts and I get that you are waiting for the switching frequency to be significantly raised before you'd be willing to 'switch' to one.

   I understand the theory that the current class D switching frequency is too low and affects the sound in the audible range but I can honestly say I don't hear any irregularities when listening intently to my system.  You may be completely correct but I'm just having a hard time faulting what I hear.  When I listen explicitly for switching frequency issues I mainly concentrate on the highest frequencies to make sure they are well extended and to make sure that spatial cues are present and the sound stage is well defined and stable both laterally and front to back.  

     Am I listening for the wrong things?

     Is there a simpler method to determine if the  switching frequency is too low and is  affecting anything in the audible band?

   I'm not really disputing the theory that a higher switching frequency  would upgrade class D amp performance.  I was just hoping to gain a better understanding of exactly how.

 Any assistance is greatly appreciated,
     Tim

























i honestly I  

I’m pretty sure that even if switching frequency becomes 1000 times higher than current standard and 1/10000000000 THD, Class-D will not convince many of audiophiles. For a lot of audiophile, ultimate transparency / cleaness / hifi is no more their goal these days.

Tim,

If you can't hear the difference, stop! :) Unless you are a QA professional, learning to tell the difference in equipment you couldn't hear before doesn't lead to better enjoyment.

I traded in my class A/AB amps after evaluating class D and finding them inaudibly different. I could not tell blindfolded which I was listening to.  I DO see potential for tweeters with rising impedances or high capacitances being too much of a challenge but that's not how I make my speakers. :)

Best,

Erik

ultimate transparency / cleaness / hifi is no more their goal these days

Those never were my goals.  Although resolution and a quiet background (similar to what you may mean by transparency/cleaness) are expected attributes in higher end gear, excellent tone, dimensionality and dynamics are more important to my enjoyment and, in my experience, it can be hard to find all three in a component.

Mitch2, well said and oh so true! 

What I’ve been trying to get across re the Class-D’s switch noise and it’s associated output filter, trying to eliminate that noise without effecting the audio band.
This is a page by the actual component manufacturer that allows the new mega expensive Technics SE-R1 to double the speed of it’s switching frequency, which in turn allows the filter to do a better job, and be less destructive to the audio band.
They still need to double it again before I’ll dip my feet into Class-D.
http://epc-co.com/epc/GaNTalk/Post/13752

Cheers George

I've been living with ICEPower based amps for six months, I don't hear any of the issues being discussed, and my speakers have extension beyond 30kHz.

Is there no need to advance in this direction in raising the switching frequency then?? Too many myself included think it is.

Quote from manufacturer of these new transitors, who btw invented the Mosfet power transistor.

" Higher PWM switching frequencies allow for a higher audio bandwidth, and hence higher-frequency output filters. As a side benefit, this higher-frequency output filter allows for smaller output filter components (especially, the Inductors) without compromising the sonic performance.

In addition to offering higher audio bandwidths (which is increasingly important for the new high-definition audio requirements), the increased PWM switching rates also allow for more moderate output filter slopes, which offer more linear performance without introducing higher levels of residual switching noise."

Cheers George

I've been living with ICEPower based amps for six months, I don't hear any of the issues being discussed, and my speakers have extension beyond 30kHz. 

 
Some folks hear the issues and others don't. Some folks are really sensitive to phase/point source issues or maybe they focus on the image across the soundstage. If someone told me that the image was off, I would just shrug and keep enjoying my gear/music because it's not something that I notice.    

Speakers shift phase much more (in opposite direction) at higher frequencies.  Imaging should be OK as long as phase in both channels match (no reason not to).  As for the switching noise - I cannot hear 500kHz, but I'm pretty sure some people here will claim they can.

I cannot hear 500kHz

Nobody can hear 500khz, it the filter that has to deal with it and what's left over and the byproducts of it that is the problem.

Read the link and carefully try to absorb it.
http://epc-co.com/epc/GaNTalk/Post/13752

Cheers George

Erik,

     I agree with you that, if I can't detect any issues in the audible range on my current class D amps due to their switching frequency being not high enough, than there is no need for concern and I should just enjoy them and my music.  Actually, this is what I've been doing since I installed the amps, I just tried to intently listen for any issues for a short period when I first heard of this theoretical issue.  

      Once an affordable class d amp with a switching frequency in the 3-5 mega hz range is on the market and there are any objective or even subjective reports that it sounds significantly better than current amps, I'll audition one.   I believe this is a more effective approach than not using class D until the theoretical  performance benefits of a 3-5 mega hz switching frequency becomes a reality, since the numerous benefits of class D amplification will not be utilized and enjoyed between now and then.      
      I would think just 2 of class D's benefits, sound quality and electricity cost savings, would be sufficiently convincing for many to switch right now.  If it's only going to get better, upgrade to class D now and then upgrade again whenever you determine future improvements are worth it.  The cost of world-class amplification has never been less expensive,as long as you're willing to be open minded, a bit more adventurous and let your ears guide you.


Enjoy,
 Tim  
 

Nobody can hear 500khz, it the filter that has to deal with it and what’s left over and the byproducts of it that is the problem.

What is left over is 500kHz. Byproducts are possible (modulation), assuming nonlinearity of motion, if tweeter can move membrane at 500kHz - no chance.

Filter or frequency have very little to do with quality of the sound, IMHO. It is related to quality of the modulator, slew rate of output devices (accuracy of the duty cycle), ringing caused by inductance and capacitance of output devices etc. Actually, increasing switching frequency can make it worse because it will reduce accuracy of the duty cycle - calling for deeper NFB. As I showed before (using 50kHz Lamm amp as an example) phase delay in audio band has nothing to do with extension and, if anything, might be beneficial since most of the speakers accelerate phase (much more) at these frequencies.

Also, increasing switching frequency will reduce amount of residue on the speaker cable but at the same time it will make it radiate much better.

H2O Audios' M250 Special Edition Mono Block Amplifiers

I saw a question on the forum about Class D amplifiers. Following the question was a comment about how class D amplifiers have distortions and lack of low level detail. I am not here to debate or disagree with anyone but just to tell of my experience with my H2O Audio M250 Special Edition mono block amps. My previous mono block amplifiers were Tube Research Labs  GT200s'. My pre-amp was and still is Tube Research Labs "The Dude". The sound was very desirable and I had that sound for a couple of years. During those years they were matched with JM Labs Nova Utopias and then Martin Logan Summit Xs'. The tube amps had the qualities that most tube lovers desire. They have rich harmonic textures, great 3D imaging and are very dynamic. They are triode amps with zero negative feedback rated at 200 watts. I must mention that I also have owned Sonic Frontiers Line Three SE amps, several Krell behemoths including the 650 mono blocks. I am a big electrostat  fan and now own the Sound Lab A3 PX speakers. Let me tell you Sound Labs are lightning quick and have tons of inner detail. But to really hear what they are capable of doing they really need an amp that just laughs at the load. Because these speakers are so revealing, any amp that has issues will be brutally exposed in seconds. That is where the H2O mono blocks come in. Boy you talk about power, grip, extension, lightning fast transients, inner detail, low level detail, it is out of this world! These amps just kick butt and have such grace and beauty. They took a long long time to break in but boy when they broke in! Never have I been so pleased with the music these things recreate. They have Ice modules in them minus the power section. The amps have huge analog toroidal power supplies. And massive caps for reserve power. I have a pretty good front end on this system. I have the Ayon transport, Ayon Skylla II DAC, Dude pr-amp. I have WireWorld power cables, interconnects, and speaker cables. My power conditioning is by Triopoint Audio it is called the Orion. Also I have the Tripoint Troy grounding system. The room is very carefully treated with sound treatments. I am just saying there is a great new world out there and most are blown away with what they hear from these amps. A friend of mine that has been in the recording industry for years said "never in his life has he heard solid state amps so free from harmonic distortions" as the H2O amps. In fact he said never has he heard ANY amp sound so beautiful period. I know I am biased but I must agree. Bottom line is do your home work about class D amps. Just like cars or anything else for that matter not all are created equal.

They have Ice modules in them minus the power section. The amps have huge analog toroidal power supplies. And massive caps for reserve power.

This is a huge step in the right direction getting rid of another point of noise (the smp), with the added lift of future higher switching frequency/filters and the benefits it brings, would spell the end of all linear amps. And Srajan's tubes below.

What Srajan Ebaen of 6 Moons said about the H2o M250's

In conclusion, I love these amps for different reasons than my tube amps.  The emotional connection is still stronger with the valves

 Cheers George 

This is a huge step in the right direction getting rid of another point of noise (the smp), with the added lift of future higher switching frequency/filters and the benefits it brings, would spell the end of all linear amps. And Srajan's tubes below.

Practically all supplies are switchers.  So called linear are very primitive -switching at 120Hz when voltage is the highest, creating a lot of high frequency noise.  Current is drawn in narrow spikes of high amplitude.  SMPS on the other hand, when done right, is far better in many respects.  It is quiet, switching at zero voltage/zero current.  It operates at high frequency that is easy to filter out (much easier than 120Hz ripple) and is line and load regulated (vs. unregulated linear supply).  It has fast response to load demands - vs. slower response caused by inductance of huge electrolytic caps. It tolerates DC on the mains (It even operates from DC).  Rowland switched completely to SMPS using them for class AB amps as well as for preamps (to lower the noise).  Benchmark improved S/N ratio by 10dB by replacing linear supply in their DAC with SMPS.  New class AB amp from Benchmark ABH2 also utilizes SMPS resulting in 132dB dynamic range.  

Why then, designers still use linear supplies with huge transformers and capacitors?  For two reasons:  First, it is very difficult to design good switcher.  Second, they follow market demand - many people believe that it has to be "linear" and heavy.

3 of the main reasons manufactures choose use smp (switchmode) power supplies.
Size/weight, efficiency, and cost to manufacture.
 
Well designed linear power supplies, are still the supply of choice for performance/noise and reliability. But they are costly and inefficient.

If/when I go to Class-D amps, I would also prefer to have a well designed linear power supply powering it.

Just quickly two that I can think of that use linear supplies for the best result they believe to power their Class-D amps are. Mark Levinson and Rogue Audio, there are many more from the upper end of town.

http://www.stereophile.com/content/mark-levinson-no53-reference-monoblock-power-amplifier#OXQH9C1XSJuv27p5.97

http://www.rogueaudio.com/PDFs/Pharoah.pdf   

Cheers George  

The main reason manufacturers of high end audio (like Rowland) use SMPS is low noise and line/load regulation.  You can find it in FAQs on his (or Benchmark) website. He uses SMPS  in preamps where size or efficiency play no role.

Yes, top manufacturers still use linear power supplies, but main reason is demand from people who, mistakenly, believe that if it has to be heavy to be good.

Yes, top manufacturers still use linear power supplies, but main reason is demand from people who, mistakenly, believe that if it has to be heavy to be good.

Sez who???

Cheers George

Well, most of people on this forum (including you) think that SMPS is noisy and linear power supply is better.  This believe comes from bad rap of noisy crude computer SMPS applications.  They don't even realize that "Linear" power supply is a primitive unregulated switcher.  I addition, many believe that when something is smaller and more efficient something else has to give (that's human nature).  They apply this believe to both SMPS and class D amplifiers (that are basically controlled SMPS).  In view of that amplifier manufacturers would be stupid not to keep using "Linear" power supplies.  Only few true pioneers like Jeff Rowland had courage to develop state of the art SMPS supplies that are extremely quiet  (noise very easy to filter out at 1MHz operation).  Even 50kHz SMPS executed well are far better than "Linear" supplies IMHO.

So much noise about nothing of real consequence.

I will of course look forward to improvements in switching frequency under the assumption that things will get even better overall down the road at least on paper. How much difference it makes practically is TBD.

George I do think you are too obsessed with this one technical issue. You should do a study to see if class d amp sound quality correlates strongly to switching frequency alone. To hell with all the rest that goes into these things if that is all the story. 

You should do a study to see if class d amp sound quality correlates strongly to switching frequency alone.

I have, done numerous bench/listening tests, and tried to come up with my own cascaded output filters like Belcanto I believe did with their 600ref monos, but doing filters this way has a other set of problems (interactive ringing) if your familiar trying cascaded filters for speaker xovers.
Mark Levinson with their no53 also tried it but that fell a bit foul with a Stereophile review/measurements.

Cheers George

 New class AB amp from Benchmark ABH2 also utilizes SMPS resulting in 132dB dynamic range.  

They had to cut costs somewhere to hit that $2995 price point. The dynamic range and THD numbers, while appearing to be unusually good, may be partly the result of using too much negative feedback. I've never heard this amp, but too much negative feedback and you can end up with a soulless amp.  

I've heard the Benchmark amp and was very impressed.